var yc = document.querySelector('#yc');
        var yc2 = document.querySelector('#yc2');
        var nr1 = document.querySelector('.nr1');
        var sz2 = document.querySelector('.sz2');
        var tiaoDu = document.querySelector('.tiaoDu');
        var shiXiao = document.querySelector('.shiXiao');

        tiaoDu.addEventListener('click', dJ);
        function dJ() {
            sz2.style.display='block';
            yc.style.display='none';
            nr1.style.display='none';
            tiaoDu.style.color='deepskyblue';
            shiXiao.style.color='black';
            yc2.style.display='block';
        }

        shiXiao.addEventListener('click', dJ2);
        function dJ2() {
            yc.style.display='block';
            sz2.style.display='none';
            nr1.style.display='block';
            shiXiao.style.color='deepskyblue';
            tiaoDu.style.color='black';
        }